Processing for generating a CG (Computer Graphics) image requires a large amount of calculation load. For this reason, an information processing apparatus which performs image generation processing in real time includes, separately from a CPU (Central Processing Unit), an image generating apparatus (a graphics processing unit) which exclusively performs image generation processing.
FIG. 1 is a flowchart indicating processes of an image generating method performed by a conventional general image generating apparatus.
The conventional general image generating apparatus first loads vertex data of each of input polygon models from an information storage device (memory) (S101). It is to be noted that the vertex data includes coordinate data indicating the positions of the vertices of each of the input polygon models, and shape data that is data other than the coordinate data. Next, the image generating apparatus performs processing for transforming the coordinates of the coordinate data in the vertex data into world coordinates, and further performs processing for transforming the world coordinates to display coordinates (S102).
Next, for each polygon composed of loaded vertex data, the image generating apparatus makes, based on the transformed coordinate data, either a clipping determination on whether or not each polygon is within a visible space or a culling determination on whether or not each polygon shows its surface that should be displayed when viewed from a view point, and thereby makes a determination on whether or not the rendering of the polygon is valid (S103). The image generating apparatus modifies data (shape data) that is other than the coordinate data in the loaded vertex data of only the polygon(s) for which the rendering is already determined to be valid (S104).
Next, the image generating apparatus performs polygon rendering processing using the modified vertex data (S105). The image generating apparatus determines whether or not the aforementioned processing is already completed for all the polygons (S106). When determining that the processing is not yet completed (“Repeat” in S106), the image generating apparatus repeats the respective processes (S101 to S105). When determining that the processing is already completed (“Completion” in S106), the image generating apparatus outputs a rendered image (S107).
A conventional general image generating method is intended to process shape data after processing coordinate data as described above. When vertex data composed of a set of coordinate data and shape data as described above is used, there is a need to load the whole vertex data that is both the coordinate data and the shape data even when only the coordinate data is to be processed. Accordingly, the image generating method entails a problem that the shape data that is unnecessary in such a case is unnecessarily loaded. Likewise, even when the shape data is to be processed, the whole vertex data is unnecessarily loaded. Accordingly, the image generating method entails a problem that the coordinate data that is unnecessary in this case is unnecessarily loaded.
In view of this, PTL (Patent Literature) 1 discloses a technique for separately managing coordinate data and shape data. This makes it possible to prevent either the shape data or the coordinate data from being unnecessarily loaded.